Hi Steven
Meraki Go is built for sites that require fewer than 20 Access Points, and that is the upper limit for the amount of Access Points allowed within the App.
If you created two networks and used two separate Go App accounts you could theoretically create a site with more than 20 Access Points, but you wouldn't be able to have visibility/manage everything at once with a singe sign on in the App.
Should you have a location that needs more than 20 Access Points, we'd suggest looking at the Meraki Enterprise solutions that are built for such a case.
All the best,
James